To date, a retort sterilization package in which contents such as foods are stored in a flexible packaging bag impermeable to oxygen or water vapor and which is subjected to retort sterilization and allows long term storage, has been known. In this kind of package, aluminum foil is often used for the packaging bag in order to ensure gas barrier properties, and, in this case, the package cannot be directly heated as it is by a microwave oven.
The contents stored in such a package are heated in two methods. One of the methods is a method in which the package is unsealed, and contents are taken out and heated by using a pot or a microwave oven. The other of the methods is a method in which the package is heated as it is in hot water.
In recent years, a packaging material in which, for example, an inorganic vapor deposited film having gas barrier properties is used instead of aluminum foil, has been developed, and a package which can be heated as it is by a microwave oven, is also put into practical use. The method in which heating in hot water is performed is advantageous in that the method can be used in an outdoor place where a microwave oven cannot be used, and a pot or a container is not soiled. Therefore, the method in which heating in hot water is performed is still widely used.
In a case where the package is heated in hot water, if the package is held by chopsticks or the like in order to take out the package from boiled water when the heating has ended, the chopsticks may slip and it may be difficult to hold the package. If the package is held with a bare hand, fingertips may contact with the boiled water or the boiled water may be splashed, so that the hand or the fingertips may be burned.
Patent Literature 1 discloses a packaging bag, for cooked foods, for solving the problems. As shown in FIG. 6, the packaging bag has, at a corner portion of a seal portion, a through hole (7) into which a chopstick can be inserted. The packaging bag can be taken out from boiled water without contact with a hand by the tip of the chopstick being inserted into the hole (7) and the hole (7) being caught with the tip of the chopstick.
However, in a case where the package as shown in FIG. 6 is actually produced and an experiment is made, the package floats in boiled water. Therefore, it is found that a problem arises that it is difficult to just insert the tip of a chopstick into the hole, and, even if the tip of the chopstick can be inserted therein, the hole is not easily caught with the tip of the chopstick since the package is horizontally positioned.